Rocket testing is a particularly difficult and costly operation. Rocket operation, however, must be thoroughly understood during the test and development phase in order to insure successful launching. Unpredicted or improper rocket operation can result in a variety of problems including failure to reach correct orbit or location, lack of control, overheating and premature shutdown.
Collecting data during rocket tests is a particularly difficult task because of the extremely hostile environment created by rocket ignition; this is particularly true in close proximity to the rocket nozzle where rocket exhaust plume temperatures are in the range of 3,000.degree. C. (6,000.degree. R.) Sensing the environment of the rocket exhaust plume would provide important information that would be helpful in analyzing rocket combustion and performance. Such information would undoubtedly include examining rocket exhaust particles and determining the mass flux distribution in the exhaust plume. Prior to use of the invention disclosed herein conventional pitot tubes and filters have been placed to collect similar data at locations distant from rocket exhaust nozzles where exhaust temperatures are reduced to near ambient temperatures.
The use of conventional probes has had distinct disadvantages due to their inability to withstand the rocket plume environment adjacent to rocket exhaust nozzles. An important disadvantage is their inability to capture an unbiased exhaust stream that hasn't been substantially attenuated and mixed with outside air. It is believed that exhaust particles carried by the exhaust stream react with air and depart the exhaust stream prior to reaching the conventional probes.
Another problem occurs when collecting particles from the exhaust stream. Particles in the rocket plume can travel in excess of six times the speed of sound. At such speeds the particles easily melt or penetrate any filter placed in their path, making collection exceedingly difficult.
A further problem with probes for use in fast moving exhaust streams is that most such probes are incapable of ingesting high speed air without aerodynamically choking. Choking the inlet flow results in much of the airstream being diverted around the probe and thereby biasing the data collected.
In view of the above it is an object of the present invention to provide a data collection probe capable of withstanding the hostile environment of rocket exhaust plume for a tixe sufficient to collect an unbiased exhaust plume sample.
Another object of this invention is to provide a data collection probe which successfully collects exhaust particles on a submicron mesh filter.
A further object of this invention is to provide a probe which is capable of ingesting high speed air flows without choking.